There are two kinds of cavalry charge in the TLNB universe. Only one of them is termed "Cavalry Charge."
1) All cavalry including light cavalry always fought by charging back and forth. This is covered in the game by the regular combat table.
2) The special, heavy-duty Cavalry Charge, covered in the game by the Charge table.
It takes trotting cavalry 2 minutes to cross one hex (246 yards/min), while the actual charge (at a gallop) would only be the last two hexes and take 3 minutes (410 yards/min). Thus, a three-hex charge would take about 5 minutes in real time.
Charges are risky. But when needed, they can be a nice gamble to puncture a hole in an otherwise solid line. If the other attacks in the area are then carried out using the just advanced infantry as a ZOC killer, then that solid line can suddenly become a lot thinner. But its always a gamble.
The Charge isn't for everybody. However, for those that do charge from time to time, do you ever have your cavalry expending their full Movement Allowance in the charge? Or are charges usually covering no more than 3-4 hexes? Is there any pattern like that? Because cavalry can’t charge through friendly units, it seems that most of the charges are from at most three hexes, and usually closer, because its so hard to set up a long string of legal, unoccupied hexes all the way to the target.
It's a good idea to use the charge when you can - it can unhinge and demoralize your opponent tremendously, and it’s usually entirely unexpected. A charge can destroy an otherwise unassailable stack. .. a high risk/high reward gamble.
A blown charge can also demoralize YOU. High strength cavalry units are gold, so throwing one away on a gamble seems foolish. Save it for when it can stun the opponent, or when the initiative could shift if it’s successful. Not something you do regularly, but because it’s not used regularly, it can have a strong morale effect on the opponent when it “goes off”.